Centrifugal pumps are the unsung heroes of industrial applications. Their reliability and efficiency make them the workhorses of the modern industrial world.
When selecting the proper chemical pump for your application, consider the chemical’s corrosivity and temperature resistance at the pumping temperature along with its viscosity and concentration. These details help determine the correct motor power, lift capacity and materials of construction for your centrifugal chemical pump.
How do centrifugal pumps work?
Centrifugal pumps work based on the forced vortex flow principle. They transform rotational energy, commonly from a motor, into kinetic energy of the fluid. This energy boosts the pressure head of the water when it leaves the impeller eye.
The pump casing, also known as the diffuser, is responsible for containing the fluid and generating pressure. Its curved funnel shape slows down the fluid’s velocity upon entry, converting kinetic energy into pressure as per Bernoulli’s principle.
A shaft is a key component of the pump and provides power for other rotating parts. It supports the rotor and is made of durable materials to prevent damage and prolong its lifespan. The shaft is equipped with bearings that absorb radial and axial forces during operation and maintain its alignment for peak performance.
When the discharge side valve is closed, the pump generates a maximum head, or static head, equal to the sum of the suction and delivery heads tu dieu khien bom. This value is the required system pressure head (NPSHA) for a given application.
If the NPSHA is too low, it will produce cavitation which is not desirable. To avoid this, it’s important to select a pump with a head capacity curve that decreases uniformly. This will ensure that the pump’s electric motors are sized appropriately to avoid overheating or burning out.
Centrifugal pump components
Centrifugal pump components are designed to transform kinetic energy into pressure energy. The casing is a sealed passage that encircles the impeller and transforms the velocity into a constant flow. The casing can be made from a variety of materials, depending on the application and environment. SF&E’s cast stainless steel parts can be found in nuclear power plants, oil refineries, and industrial applications.
Liquid enters the casing through a suction valve and flows into the volute. The fluid is then accelerated by friction between the impeller vanes and the casing walls, and then thrown to the outer periphery of the volute where the kinetic energy is converted to pressure. The casing walls can be lined with rubber, graphite, or nickel aluminum bronze.
The shaft seal prevents leakage between the impeller and other pump components. It also protects against contamination and corrosion. Shaft sealing can be done using a range of methods, including ball bearings, sleeve bearings, and pivot shoe bearings.
The foot value and strainer are two parts that control the suction and discharge of the pump. The foot valve is a one way valve that opens upward, and the strainer keeps foreign matter out of the pump. The piping connecting the foot valve to the inlet of the impeller is known as the suction pipe. It is a one way connection and can be made from a wide range of materials.
Centrifugal pump types
Centrifugal pumps are very useful tools to transfer liquids and thereby enable efficient production of various types of products. They are also useful in many industrial processes, for example water supply, wastewater treatment, oil and gas, power generation, chemical processing and HVAC (Heating, Ventilation and Air Conditioning).
A centrifugal pump converts rotational kinetic energy into hydrodynamic energy to force fluid movement and elevate the liquid’s pressure. This mechanical energy is supplied by an electric motor which turns a shaft attached to the impeller. The rotating shaft imparts energy to the fluid through centrifugal force, propelling it radially outwards into a diffuser or volute casing. The remaining kinetic energy is converted into pressure head by the casing’s increasing section, which raises the liquid above its suction level and allows it to be delivered from the pump.
The fluids which are processed using these centrifugal pumps can often be very corrosive and the pump components come in contact with them, so it is important that they are made of corrosion-resistant materials. Cast iron offers a high tensile strength and durability and can withstand high pressures, while stainless steel provides excellent resistance to chemicals and rust. Graphite monolithic ceramic and nickel aluminum bronze are also suitable for use in highly corrosive applications.
There are several different types of centrifugal pumps, and their classifications depend on several factors, including the flow type (suction or discharge), pump height and hydraulic efficiency, the number of stages and casing. For example, a multi-stage centrifugal pump has multiple impellers which contribute to the overall increase in pressure, and is used in applications where a significant net positive suction head is required.
Centrifugal pump applications
Centrifugal pumps are used to pump a wide range of liquids in various industries. They are often used in chemical, oil energy, power generation and food production applications. They are well suited to handle thick and viscous fluids such as slurries. This is because of the smooth, rotating motion they produce which can provide higher head pressure and a more even discharge of fluids in contrast to positive displacement pumps that have pulsating flow motion.
Once the fluid leaves the impeller, it enters the casing where its kinetic energy is converted into pressure energy. This allows the fluid to push through the casing with a high velocity and then into the connected piping system.
Casing design varies based on the type of liquid, desired performance and application. Generally, they are made from a variety of materials to meet the needs of the particular liquid being pumped. A lining can also be used to protect the casing from damage caused by chemical attacks.
It is important to select a centrifugal pump that operates at its BEP (Best Efficiency Point) for the specific speed, size and impeller. Operating the pump at this point maximizes energy efficiency and extends seal and bearing life. This can help to reduce maintenance costs and energy bills, which is especially important in industrial settings where energy costs are usually one of the largest components of the overall pumping system.
